Changed format of test data for word selection test - each test's data in own directory

idea/testData/wordSelection/ValueArguments/0.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    foo(<selection><caret>1</selection>, 2)
+}

idea/testData/wordSelection/ValueArguments/1.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    foo(<selection><caret>1, 2</selection>)
+}